linux-kernel - Re: [PATCH v2 02/15] clk: renesas: r9a09g057: Add clock and reset entries for DSI and LCDC

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Message-ID: <CAMuHMdWj91VbxRbb_pZ23ySbvjzzgfTgy83GXTEtC9CAS=d5Sg@mail.gmail.com>
Date: Tue, 15 Apr 2025 17:50:59 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Biju Das <biju.das.jz@...renesas.com>, 
	Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Magnus Damm <magnus.damm@...il.com>, dri-devel@...ts.freedesktop.org, 
	devicetree@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Tommaso Merciai <tommaso.merciai.xr@...renesas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v2 02/15] clk: renesas: r9a09g057: Add clock and reset
 entries for DSI and LCDC

Hi Prabhakar,

On Tue, 8 Apr 2025 at 22:09, Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Add clock and reset entries for the DSI and LCDC peripherals.
>
> Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> v1->v2:
> - No changes

You did change CSDIV0_DIVCTL2 to the NO_RMW-variant...

> --- a/drivers/clk/renesas/r9a09g057-cpg.c
> +++ b/drivers/clk/renesas/r9a09g057-cpg.c

> @@ -148,6 +182,12 @@ static const struct cpg_core_clk r9a09g057_core_clks[] __initconst = {
>         DEF_SMUX(".smux2_gbe0_rxclk", CLK_SMUX2_GBE0_RXCLK, SSEL0_SELCTL3, smux2_gbe0_rxclk),
>         DEF_SMUX(".smux2_gbe1_txclk", CLK_SMUX2_GBE1_TXCLK, SSEL1_SELCTL0, smux2_gbe1_txclk),
>         DEF_SMUX(".smux2_gbe1_rxclk", CLK_SMUX2_GBE1_RXCLK, SSEL1_SELCTL1, smux2_gbe1_rxclk),
> +       DEF_FIXED(".plleth_lpclk_div4", CLK_DIV_PLLETH_LPCLK, CLK_PLLETH, 1, 4),
> +       DEF_CSDIV(".plleth_lpclk", CLK_CSDIV_PLLETH_LPCLK, CLK_DIV_PLLETH_LPCLK,
> +                 CSDIV0_DIVCTL2, dtable_16_128),

The clock names look strange to me: "plleth_lpclk_div4" sounds like it is
"plleth_lpclk" divided by four, but that is not the case here.

> +
> +       DEF_PLLDSI_DIV(".plldsi_sdiv2", CLK_PLLDSI_SDIV2, CLK_PLLDSI,
> +                      CSDIV1_DIVCTL2, dtable_2_32),
>
>         DEF_DDIV(".pllgpu_gear", CLK_PLLGPU_GEAR, CLK_PLLGPU, CDDIV3_DIVCTL1, dtable_2_64),
>

> --- a/drivers/clk/renesas/rzv2h-cpg.h
> +++ b/drivers/clk/renesas/rzv2h-cpg.h

> @@ -117,6 +118,8 @@ struct smuxed {
>
>  #define CSDIV0_DIVCTL0 DDIV_PACK(CPG_CSDIV0, 0, 2, CSDIV_NO_MON)
>  #define CSDIV0_DIVCTL1 DDIV_PACK(CPG_CSDIV0, 4, 2, CSDIV_NO_MON)
> +#define CSDIV0_DIVCTL2 DDIV_PACK_NO_RMW(CPG_CSDIV0, 8, 2, CSDIV_NO_MON)

The documentation says:

    DIVCTL2[3:2] is reserved.
    When writing, read modify write is needed.

So the NO_RMW-logic seems to be inverted?

> +#define CSDIV1_DIVCTL2 DDIV_PACK(CPG_CSDIV1, 8, 4, CSDIV_NO_MON)
>
>  #define SSEL0_SELCTL2  SMUX_PACK(CPG_SSEL0, 8, 1)
>  #define SSEL0_SELCTL3  SMUX_PACK(CPG_SSEL0, 12, 1)

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds